Flyweight(享元模式)

import java.util.Hashtable;

/**
 * 享元模式
 * @author TMAC-J
 * 享元模式一般和工廠模式一起使用，但此處為了更好說明，只用享元模式
 * 定義：享元模式針對於是一種以時間來切換空間的方式，其公用同一實例，線程池，string都是其應用
 */
public class FlyweightPattern {
    
     public class Flyweight{
        private Hashtable<String, Object> objs = new Hashtable<String, Object>();
        public Object  createObj(String className) throws InstantiationException, IllegalAccessException, ClassNotFoundException{
            if(objs.get(className) == null){
                Object obj = Class.forName(className).newInstance();
                return obj;
            }
            else{
                return objs.get(className);
            }
        }
     }
    
    public class A {}
    
    public class B{}
    
    public void test() throws InstantiationException, IllegalAccessException, ClassNotFoundException{
        Flyweight flyweight = new Flyweight();
        flyweight.createObj("A");
        flyweight.createObj("B");
    }
    
}